Now take your maximum depth and multiply this number by 2. Take this figure and add 2 for your overhang (this is counted as 1' for each side multiplied by 2). Now take your total and add to your maximum width and add the same number to your maximum length. You will most likely need to round up to match one on the pre-cut liner sizes.

Here is an example: Maximum width = 5' Maximum length = 10' Maximum depth = 2.5' (2 x's 2.5' = 5' + 2 = 7) (7 + 5 = 12' width) (7 + 10 = 17' length) So you would need a liner close to 12' x 17' and the closest would be 15' x 20'. You could also back fill, re-measure and see if you can get your measurements to 10' x 15'.